MUSCOVITE is the white mica found in tabular crystals that can be cleaved into flexible and elastic sheets. It can be scratched and cut easily with a knife or shears. BIOTITE is an amber-colored to black mica. Like muscovite it is flexible and elastic, but it is slightly more brittle. TOURMALINE crystals occur in triangular prisms with the corners bevelled so as to give them a rounded appearance. They lack cleavage, are very brittle, and will scratch glass. Black is their usual color, but red and green varieties are present in many pegmatites. SPODUMENE crystals are white to pale rose in color, and they occur as flattened prisms with bevelled corners. They cleave parallel to the surfaces bevelling the corners. The mineral is much harder than a knife, and the cleavage surfaces have a lustrous, slightly satiny appearance. RADIOACTIVE MINERALS occur in many pegmatites and metamorphic rocks of this region. The species which have been formed as a result of recent alteration are brilliant golden or green encrustations in cracks or on a pitchy-black nucleus. The most abundant ones are uranite, autunite and torbernite. Older primary or source minerals are pitchy-black and are surrounded by a narrow rusty red zone or “halo,” ¹/₁₆ to ⅛ inch wide; an elongate species resembling a rusty hand-made nail is allanite; the more pitchy, irregular-shaped mineral is usually uraninite or pitchblende. Other minerals found in pegmatites in the Connecticut Valley region include beryl, apatite, zircon, garnet, fluorite and lepidolite. Most of the minerals in normal igneous rocks are too minute to be recognized easily, but a few have distinctive characteristics which serve to identify them. QUARTZ is a hard, dark, glassy-looking mineral without cleavage. ORTHOCLASE and MICROCLINE feldspar are hard, flesh-colored (occasionally white) minerals with flat cleavage surfaces. The minerals making the white lathlike mosaic on the weathered surface of the Range at the Mount Holyoke House are LABRADORITE feldspar. They are about ¼ inch long and ¹/₅₀ inch thick—too small to permit testing by ordinary physical methods, although unweathered pieces have essentially the same physical properties as orthoclase and microcline. The MICAS are flaky and reflect light like minute pieces of tinfoil; muscovite is white, and biotite is amber-colored to black. CHLORITE resembles mica but is less lustrous and is dark green. Some minerals of igneous rocks do not appear in pegmatites. Among them is OLIVINE, which has almost the same color as chlorite but is harder than a knife and is massive or granular. It is commonly associated with massive green SERPENTINE, which is softer than a knife. These three minerals are especially abundant in rocks found in the vicinity of Blandford, Massachusetts, and Dover and Chester, Vermont.